5th Gen SS Auto: Everything you ever wanted to know.

[gerhard]

Why 15,000 miles? Most Honda dealers will tell you it's a really good idea to change the ATF every 30,000 miles. (Even though the Service Manual says 90,000 and 60,000 miles depending on driving conditions. [what BS!]) However, you can only change 3 QTs at a time with a standard drain. As such, if you change the ATF every 15,000 miles you are removing particulates and refreshing the ATF's additive package (which prevents the acidic worn out ATF from effecting the transmission and keeps the seals in good condition).

Lastly, if you live in climates where you are going to face sub-zero temperatures, then you should consider using a synthetic ATF / Honda ATF mix. Generally, you can use 50%-60% Honda ATF and AMSOIL or Mobil 1 Dexron III ATFs. You can also use B&M "Synthetic Trick Shift" ATF, it flows to -65 degrees F, but is better mixed with AMSOIL or Mobil 1 as well. You will likely need to have at least 50% Honda ATF in your transmission to maintain proper shifting characteristics. It’s possible that some of the current market ATFs have been reformulated to meet the friction requirements of Honda ATF, but you can not count on that!

Interestingly, Honda ATF only thickens slightly at 0 degrees F. B&M, AMSOIL, and Mobil 1 have virtually no change at 0 degrees F and that's why the mixture works so well. (Better cold shifting, slightly better thermal transfer properties, improved lubricating properties, etc...) Keep in mind that if you use B&M "Synthetic” Trick Shift ATF it's not actually a truly synthetic fluid and will need to be changed at the proper 15,000 mile interval. B&M does have much better cold shift characteristics, but that’s because it’s a thinner ATF to begin with. (Even with synthetic ATF in the tranny you should change it regularly anyway, but especially when using Honda ATF or B&M STS.)